These are the Out Front compact composite scissor wheel locks. They are in great shape except for a broken spring in one of them. I found replacement spring at southwestmedical.com for a pretty reasonable $4.50, but it also had $24.90 shipping. So $30 for one tiny spring. I only paid $100 for two new entire wheel locks! Does anyone have an alternate source? Even though these locks have a poor reputation for reliability, I really like using them.